High accuracy metrology has been utilized in the manufacturing context for a number of years. For example, many manufacturers have traditionally utilized a coordinate measuring machine (“CMM”) or calipers to provide measurements for determining adherence to manufacturing tolerances, such as for the manufacture of an automobile engine. While CMM's are very accurate, they are also expensive, large, and their configuration is dependent on the specific application for which they are designed.
While calipers are relatively inexpensive, they are also inflexible. Thus, they are not able to measure a broad variety of shapes and sizes.
In about the past decade or so, articulated arm-type CMM devices have begun to replace the gantry-type CMM. An articulated arm-type device utilizes a mechanical structure that resembles a robot arm. While these devices are not as accurate as a CMM and are still expensive, they tend to be less expensive than CMM's. Such devices are utilized for computer animation, three-dimensional shape digitizing, metrology, and in some medical applications. Such devices are typically grounded to a fixed reference surface. Thus, in order to use a device in a different place, the device must be detached from the surface and relocated, which limits the device's flexibility.